(1) Field of the Invention
The present invention relates to an indirect extrusion press and more particularly to an indirect extrusion press in which the charging of a billet into a container from a pressure stem side provided with a seal block at the fore end thereof can be done without dropping of the billet and without the need for lengthening the moving stroke of the container, by utilizing a retreat period of the container, to thereby shorten the press cycle time.
(2) Description of the Prior Art
In an indirect extrusion press having a seal block at the fore end of a pressure stem, one end of a container is closed with the seal block and in this state the container is fitted over a die stem whereby the billet is extruded through the die stem.
In such type of indirect extrusion presses, however, there arise problems particularly in connection with charging of a billet into the container.
For example, reference is here made to FIG. 1 illustrating a conventional press of this type, in which in charging a billet 4 which has been loaded onto the press axis through a billet loader 5, into a container 2 fitted on a die stem 3, the billet 4 is maintained at its maximum length or a billet pusher 6 is inserted into a pressure stem having a seal block 1 so as to extend through the seal block 1. In this conventional press, the billet 4 must be held in a gripped state between the seal block 1 and the die stem 3 or between the billet pusher 6 and the die stem 3 at the time of charging of the billet 4 into the container 2. In this state, however, the billet may drop because the billet loader 5 is in a retracted position.
Referring now to FIG. 2, there is illustrated another conventional example, in which one end of the container 2 is closed with the seal block 1, and the billet 4 which has been carried in by the billet loader 5 can be charged into the container 2 from the die stem 3 side. In this conventional extrusion press of FIG. 2, the problem of dropping of the billet 4 involved in the press of FIG. 1 can be overcome, but a spacing corresponding to the length of the billet 4 must be provided between the container 2 and the die stem 3, thus resulting in an increase of the overall press length. Besides, a billet charge stroke L2 and a container retreat stroke M2 can become long as compared with a billet charge stroke L1 and a container retreat retracting stroke M1 in the extrusion press of FIG. 1, thus resulting in the press cycle time becoming longer, which gives rise to a problem in terms of production efficiency.